[PATCH] D142359: [TTI][AArch64] Cost model vector INS instructions

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added a comment.

In D142359#4131731 <https://reviews.llvm.org/D142359#4131731>, @dmgreen wrote:

> I was expecting that to be similar to the other fmul+fadd vs fma issue we have seen elsewhere, but I'm not sure it is. Does it reduce the value to a single element again?
>
> As for a few examples, this case is a little worse. I'm not sure if it is using bad costs, but the slp vectorization seems to reach through a phi and the result when put through llc is mostly just more instructions: https://godbolt.org/z/z6hnEcPG1.
> Another case which is perhaps simpler is this "distance" one from cmsisdsp: https://godbolt.org/z/1xz7GP3fM. It looks like something might be being scalarized, but again I've not looked into the details.
>
> There are some nice improvements too, if we can get the regressions hopefully fixed.

Thank you so much for these reproducers. They are the best and most concrete reproducer I've got so far, so I will be looking into them.


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